Copolymers for treating construction aggregates

ABSTRACT

The present invention provides methods, admixture compositions for treating clay-bearing aggregates used for construction purposes, and aggregate compositions for construction purposes. The clay-bearing aggregates are treated with a cationic copolymer made from two and preferably three different monomer components. Cementitious compositions containing the treated aggregates are also described.

FIELD OF THE INVENTION

This invention relates to the treatment of sand aggregates used formaking construction materials, and more particularly to the mitigationof clay in construction aggregates using a cationic copolymer made fromtwo or more monomers, one of which is quarternized.

BACKGROUND OF THE INVENTION

It is known that sand aggregates used in making construction materialssuch as concrete can contain clay materials that are detrimental to theconcrete and/or to the efficiency of plasticizers used in the concrete.

For example, U.S. Pat. Nos. 6,352,952 and 6,670,415, owned by the commonassignee hereof, Jardine et al. disclosed that certain clays, whichexpanded when in contact with water, were responsible for adverselyaffecting the dosage efficiency of “EO/PO” type superplastizicers (e.g.,which contained ethylene oxide and propylene oxide groups). Jardine etal. taught that clay-activity-modifying agents, such as organic cations(such as quaternary amines which have a strong affinity for cationicexchange with clay), could be introduced to the clay before, during, orafter water is introduced to the clay.

As another example, in U.S. Ser. No. 11,575,612 (Publ. No. 2007/0287794A1) and U.S. Ser. No. 1111/575,607 (Publ. No. 2008/0060556 A1), Jacquetet al. disclosed compositions and methods for inerting clays in sandaggregates intended for use in preparing concrete. The compositionscould include monomers already containing a cationic quaternary aminefunctional group: such as diallyldialkyl ammonium, quaternized(meth)acrylates of dialkylaminoalkyl and (meth)acrylamides N-substitutedby a quaternized dialkylaminoalkyl. Particularly preferred were cationicpolymers obtained by polycondensation of dimethylamine andepichlorohydrin.

SUMMARY OF THE INVENTION

The present invention relates to the treatment of clay-bearingaggregates which are used in the preparation of concrete, mortar, andasphalt, and particularly to the use of a copolymer obtained throughpolymerization of certain monomer components, as will be moreparticularly described hereinafter.

The use of the copolymer can lead to improvement of properties in thecementitious compositions, such as workability without increasing waterdemand, and to reducing the effort needed to wash and dispose of theclay.

An exemplary method of the present invention thus comprises: introducingto clay-bearing sand aggregates, in an amount of 5% to 60% based onweight of clay, at least one copolymer obtained from monomer components(A), (B), and optionally (C), as follows:

(A) in an amount of 0.10-0.95 mole, a first monomer component selectedfrom quarternized vinylpyridine or other monomer represented by one offollowing structures

wherein

R₁, R₂, and R₃ each independently represent hydrogen, —CH₃, or —COOH;

R₄, R₅, R₆, R₇, and R₈ each independently represent a C₁-C₄ alkyl group;

R₉ and R₁₀ each independently represent hydrogen or —CH₃;

Z₁ represents —O— or —NH—;

Y₁ represents —CH₂CH(OH)CH₂— or —(CH₂)_(n)— wherein “n” represents aninteger of 0 to 6; and

X represents a halide, pseudohalide, or sulfate; and

(B) in an amount of 0.05-0.90 mole, a second monomer represented by thestructural formula

wherein

R₁₁, R₁₂, R₁₃, R₁₄, and R₁₅ each independently represent hydrogen orC₁-C₃ alkyl;

Z₂ represents —O—, —COO—, —OCO—, —COHN—, or —NHCO—;

Y₂ represents —(CH₂)_(n)— wherein “n” represents an integer of 0 to 6;and

“m” represents an integer of 10 to 200; and

(C) in an amount of 0-0.20 mole, a third monomer selected from the groupconsisting of acrylate, methacrylate, acrylamide, methacrylamide, alkylor dialkyl acrylamide, and methacrylamide monomers.

The present invention also provides an aggregate composition made fromthe foregoing method. The aggregate composition can be combined with acement binder to form a mortar or concrete, or combined with asphalticcomposition to provide asphalt compositions, and can be used generallyto form construction material compositions. The aggregate compositioncan alternatively be combined with one or more conventional admixturechemicals, such as a water reducer (e.g., superplasticizer) admixture;and may contain both a cement binder and water reducer.

The present invention also provides admixture compositions containingthe above-described copolymer for treating construction materialcompositions in combination with at least one chemical admixtureconventionally used for modifying hydratable mortar or concrete, such asone or more water reducing admixtures (e.g., a polycarboxylate combpolymer superplastizicizer), or other conventional admixture oradmixtures, as will be further described in detail hereinafter.

Exemplary admixture compositions of the invention may be introduced toclay-bearing aggregates at or after the quarry or processing at anaggregates mine, or before or at the concrete mix plant, where theaggregates are combined with cement to provide mortar or concretecompositions.

Further advantages and features of the invention will be described infurther detail hereinafter.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present invention pertains to method and compositions for treatingclays in sand aggregates intended for construction material purposes.

The clays may be swelling clays of the 2:1 type (such as smectite typeclays) or also of type 1:1 (such as kaolinite) or of the 2:1:1 type(such as chlorite). The term “clays” has referred to aluminum and/ormagnesium silicates, including phyllosilicates having a lamellarstructure, but this term may also refer to clays not having suchstructures, such as amorphous clays. The present invention is notlimited to swelling clays, which have been seen to absorb EO/POsuperplasticizers as previously mentioned in the background, but alsoincludes the use of clays that may directly affect the properties ofconstruction materials whether in their wet or hardened state. Clayswhich are commonly found in sands include, for example, montmorillonite,illite, kaolinite, muscovite, and chlorite. These are also included inthe methods and compositions of the invention.

The clay-bearing sands which are treated by the method of the presentinvention may be used in cementitious materials, whether hydratable ornot, and such cementitious materials include concrete, mortar, andasphalt, which may be used in structural building and constructionapplications, roadways, foundations, civil engineering applications, aswell as in precast and prefabrication applications.

The term “sand” as used herein shall mean and refer to aggregateparticles usually used for construction materials such as concrete,mortar, and asphalt, and this typically involves granular particles ofaverage size between 0 and 8 mm, preferably between 2 and 6 mm. Sandaggregates may comprise calciferous, siliceous or siliceous limestoneminerals. Such sands may be natural sand (e.g., derived from glacial,alluvial, or marine deposits which are typically weathered such that theparticles have smooth surfaces) or may be of the “manufactured” typemade using mechanical crushers or grinding devices.

The construction materials in which the sand is used include hydratablecementitious compositions, such as mortar and concrete, and also mayinvolve asphalt compositions.

The term “cement” as used herein includes hydratable cement and Portlandcement which is produced by pulverizing clinker consisting of hydrauliccalcium silicates and one or more forms of calcium sulfate (e.g.,gypsum) as an interground additive. Typically, Portland cement iscombined with one or more supplemental cementitious materials, such asPortland cement, fly ash, granulated blast furnace slag, limestone,natural pozzolans, or mixtures thereof, and provided as a blend. Theterm “cementitious” refers to materials that comprise Portland cement orwhich otherwise function as a binder to hold together fine aggregates(e.g., sand), coarse aggregates (e.g., crushed gravel), or mixturesthereof.

The term “hydratable” is intended to refer to cement or cementitiousmaterials that are hardened by chemical interaction with water. Portlandcement clinker is a partially fused mass primarily composed ofhydratable calcium silicates. The calcium silicates are essentially amixture of tricalcium silicate (3CaO.SiO₂ “C₃S” in cement chemistsnotation) and dicalcium silicate (2CaO.SiO₂, “C₂S”) in which the formeris the dominant form, with lesser amounts of tricalcium aluminate(3CaO.Al₂O₃, “C₃A”) and tetracalcium aluminoferrite (4CaO.Al₂O₃.Fe₂O₃,“C₄AF”). See e.g., Dodson, Vance H., Concrete Admixtures (Van NostrandReinhold, New York N.Y. 1990), page 1.

The term “concrete” will be used herein generally to refer to ahydratable cementitious mixture comprising water, cement, sand, usuallya coarse aggregate such as crushed gravel, and optional chemicaladmixture(s).

As used herein, the term “copolymer” or “polymer” as used herein refersto compounds containing at least two different monomer components(designated as “A” and “B”) and optionally at least three differentmonomer components (further including optional monomer designated as“C”).

The copolymers of the invention are preferably made by conventionaladdition polymerization techniques such as radical polymerization.Preferably, the polymerization is conducted in aqueous solution using awater soluble free radical initiator including peroxides, such ashydrogen peroxide; persulfates, such as ammonium, sodium, or potassiumpersulfate; and water soluble azo initiators. The copolymers can also bemade such as by grafting polyoxyalkylene onto the polymer main chain.Preferably, the molecular weight range of the copolymer is 1000-100,000;more preferably 2,000-60,000; and most preferably the molecular weightrange is 5,000-50,000.

As summarized above, exemplary methods of the present invention involveintroducing the copolymer to clay-bearing aggregates at a quarry ormining plant, where the aggregate is manufactured or washed, or thecopolymer can be introduced to the clay-bearing aggregates at a concretemixing plant, where cement and aggregates are combined to make ahydratable mortar or concrete. In further exemplary methods, thecopolymer can also be added directly into the mortar or concrete,separately or together or in mixture with one or more conventionaladmixtures, such as water reducers (including superplasticizers), and/orother admixtures.

Of the admixtures, so-called EO/PO type polymers, which have ethyleneoxide (“EO”) and/or propylene oxide (“PO”) groups and polycarboxylategroups, are preferred. Cement dispersants contemplated for use in theinvention include EO/PO polymers and EO/PO comb polymers, as describedfor example in U.S. Pat. Nos. 6,352,952 B1 and 6,670,415 B2 of Jardineet al., which mentioned the polymers taught in U.S. Pat. No. 5,393,343assigned to W. R. Grace & Co.-Conn. These polymers are available fromGrace under the trade name “ADVA®”. Another exemplary cement dispersantpolymer, also containing EO/PO groups, is obtained by polymerization ofmaleic anhydride and an ethylenically-polymerizable polyalkylene, astaught in U.S. Pat. No. 4,471,100. In addition, EO/PO-group-containingcement dispersant polymers are taught in U.S. Pat. No. 6,569,234 B2 andU.S. Pat. No. 5,661,206. The amount of such polycarboxylate cementdispersants used within concrete may be in accordance with conventionaluse (e.g., 0.05% to 0.25% based on weight of active polymer to weight ofcementitious material).

Thus, exemplary admixture compositions of the invention comprise: theabove-described copolymer and at least one polycarboxylate cementdispersant, which is preferably a polycarboxylate comb polymer having EOand PO groups, as described above.

As summarized above, an exemplary method of the present inventioncomprises: introducing to clay-bearing sand aggregates, in an amount of5% to 60% based on weight of clay treated, at least one copolymerobtained from monomer components (A), (B), and optionally (C), asfollows:

(A) in an amount of 0.10-0.95 mole, a first monomer selected fromquarternized vinylpyridine or other monomer represented by one of thefollowing structures

wherein R₁, R₂, and R₃ each independently represent hydrogen, —CH₃, or—COOH; R₄, R₅, R₆, R₇, and R₈ each independently represent a C₁-C₄ alkylgroup; R₉ and R₁₀ each independently represent hydrogen or —CH₃; Z₁represents —O— or —NH—; Y₁ represents —CH₂CH(OH)CH₂— or —(CH₂)_(n)—wherein “n” represents an integer of 0 to 6; and X represents a halide,pseudohalide, or sulfate; and

(B) in an amount of 0.05-0.90 mole, a second monomer represented by thestructural formula

wherein R₁₁, R₁₂, R₁₃, R₁₄, and R₁₅ each independently representhydrogen or C₁ to C₃ alkyl; Z₂ represents —O—, —COO—, —OCO—, —COHN—, or—NHCO—; Y₂ represents —(CH₂)_(n)— wherein “n” represents an integer of 0to 6; and “m” represents an integer of 10 to 200 (and more preferablyrepresents an integer of 10-100, and most preferably an integer of20-70); and

(C) in an amount of 0-0.20 mole, a third monomer selected from the groupconsisting of acrylate, methacrylate, acrylamide, methacrylamide, alkylor dialkyl acrylamide, and methacrylamide monomers.

Monomer component (A) can be chosen, for example, from a list includingdiallyl dimethyl ammonium chloride (DADMAC), 2-acryloyloxyethyltrimethyl ammonium chloride (AETAC), 2-methacryloyloxyethyl trimethylammonium chloride (METAC), acrylamidopropyl trimethyl ammonium chloride(APTMAC), methacrylamidopropyl trimethyl ammonium chloride (MPTMAC),quaternized N-vinylpyridine, quaternized 2-vinylpyridine, quaternized4-vinylpyridine.

As mentioned above regarding the first monomer component, “X” canrepresent a halide, pseudohalide, or a sulfate. Preferred halides arechloride and bromide. A pseudohalide is an anion that shares commonstructural and electronic features with the halides. Examples includecyanide, thiocyanate, azidothiocarbonate, selenocyanate, tellurocyanate,cyanate, azide, and their structural isomers.

Monomer component (B) can be chosen, for example, frommethoxypolyethylene glycol acrylate, methoxypolyethylene glycolmethacrylate, methoxypoly(ethylene-propylene glycol) acrylate,methoxypoly(ethylene-propylene glycol) methacrylate, alkoxypolyethyleneglycol monoallyl ether, alkoxypoly(ethylene-propylene glycol) monoallylether, wherein the nominal molecular weight of the polyalkylene oxide isin the range of 500 to 8,000.

Monomer component (C) can be chosen, for example, from a group including2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropylacrylate, 2-hydroxypropyl methacrylate, acrylamide, methacrylamide,N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamide,N-methylol methacrylamide, N-isopropyl acrylamide, N,N-dimethylacrylamide, N,N-dimethyl methacrylamide.

In preferred embodiments of the invention, the molar ratio (A:B) ofmonomer component (A) to monomer component (B) is 0.20:0.80 to0.90:0.10; and, more preferably, the molar ratio (A:B) is 0.50:0.50 to0.85:0.15.

In other preferred embodiments, R₇ and R₈ of the above-describedcopolymer are —CH₃; and R₉ and R₁₀ of said copolymer are hydrogen.

In other preferred embodiments, Z₁ is oxygen and Y₁ is —CH₂CH₂—.

In still further embodiments, Z₁ is —NH— and Y₁ is —CH₂CH₂CH₂—.

In other embodiments of the invention, the above-described copolymer maycontain two or more monomer components which are both represented by thestructure of the first monomer (A). In other embodiments of theinvention, the copolymer may contain two or more monomer componentswhich are both represented by the structure of the second monomer (B).

In preferred embodiments of the invention, the copolymer has aBrookfield viscosity of 20 to 2000 Centipoise (hereinafter “cps”) at 70wt % aqueous solution at 20° C.; and, more preferably, the copolymer hasa Brookfield viscosity of 60 to 500 cps at 70 wt % aqueous solution at20° C.

Preferably, in methods and compositions of the invention, the amount ofthe copolymer introduced to the clay is 10% to 40%, and more preferably10% to 30% by weight, based on the weight of the clay being treated.

In one exemplary method of the invention, the sand treated by thecopolymer may then be combined with the components for making concrete,mortar, or asphalt. The present invention also relates to concrete,mortar, or asphalt containing the sand, clay, and above-describedcopolymer. The copolymer may be introduced to the sand by application tothe clay-containing aggregates at the quarry or mine, or at the concretemix plant where the aggregates are combined with cement to formhydratable mortar or concrete. The copolymer may be incorporated intothe aggregates at the concrete mix plant before the cement binder isadded, or into dry or wet mortar or concrete.

Thus, the invention also provides chemical admixtures containing thecopolymer described above as well as to cementitious compositionscontaining said copolymer. It is contemplated that conventional chemicaladmixtures may be used in combination with the above-described copolymerin exemplary methods, admixture compositions, and cementitiouscompositions of the invention. Such conventional admixtures may includefor example, lignin sulfonate, naphthalene sulfonate formaldehydecondensate (NSFC), melamine sulfonate formaldehyde condensate (MSFC),polycarboxylate polymer cement dispersants (such as the EO-PO typedescribed above), gluconate, set retarders, set accelerators, defoamers,air entraining agents, surface active agents, or mixtures thereof.

Hence, the present invention also provides chemical admixturecompositions comprising the above-mentioned copolymer in combinationwith at least one conventional admixture, such as water reducingadmixtures (e.g., superplasticizers), defoamers, air entraining agents,surfactants, or mixtures thereof.

Exemplary cementitious compositions of the invention comprise at leastone hydratable cement binder in combination with the above-describedcopolymer for treating clay, and optionally aggregates containing claywhich requires the treatment described herein.

While the invention is described herein using a limited number ofembodiments, these specific embodiments are not intended to limit thescope of the invention as otherwise described and claimed herein.Modification and variations from the described embodiments exist. Morespecifically, the following examples are given as a specificillustration of embodiments of the claimed invention. It should beunderstood that the invention is not limited to the specific details setforth in the examples. All parts and percentages in the examples, aswell as in the remainder of the specification, are by percentage weightunless otherwise specified.

Example 1

A solution containing diallyldimethylammonium chloride (DADMAC) aqueoussolution (59.7 g, 65% solid) and distilled water (120 ml) weretransferred into a 500 ml flask equipped with a condenser, a mechanicalstirrer, a thermocouple and a nitrogen inlet. The system was purged withnitrogen to remove air, and temperature of the solution was increased to70 degrees Celcius. Into the flask, 50 ml of an aqueous solution ofpolyethylene glycol methacrylate (475-PEG-MA, 20.1 g) and3-mercaptopropionic acid (3-MPA, 2 ml), and 20 ml aqueous solution ofammonium persulfate (APS, 2.86 g) were added simultaneously into theflask over a period of 8 hours. After addition, the polymerizationreaction was held at 70° C. for 12 hours, then stopped by cooling toambient temperature. The resulting polymer is called Polymer A.

Using the same procedure, the following polymers were synthesized andsummarized in Table 1 below.

TABLE 1 Cationic graft polymer synthesized via procedure described inExample 1. 375-PPG- PEG-MA MA Cationic Monomer Brookfield Mn Wt % Wt%^(a) Type Wt % Viscosity^(b) Polymer A  475 34 0 DADMAC 66 NA Polymer B1100 55 0 DADMAC 45 100 Polymer C 1100 27 10 DADMAC 63 120 Polymer D — 044 DADMAC 56 120 ^(a)375⁻PPG-MA, poly(propylene glycol) methacrylate, Mn= 375. ^(b)Brookfield viscosity was measured at 70 wt % solution, 20° C.using spindle 02 on model DV-I+ Brookfield viscometer.

Example 2

A 500 ml flask equipped with a condenser, a mechanical stirrer, athermocouple and a nitrogen inlet, containing 100 ml water was purgedwith nitrogen then heated to 70° C.

Three aqueous solutions were added into the reaction flasksimultaneously over a period of 8 hours: (1) 50 ml aqueous solution of2-(methacryloyloxy)ethyl trimethylammonium chloride (METAC, 26.8 g); (2)50 ml aqueous solution of 1100-PEG-MA (25 g) and 3-MPA (2 ml); and (3)50 ml aqueous solution of APS (2.3 g). After addition, the reaction washold at 70° C. for 12 hours then stopped by cooling to ambienttemperature. The resulting polymer is called Polymer E.

Using the same procedure, the following polymers were synthesized andsummarized in Table 2.

TABLE 2 Cationic graft polymer synthesized via procedure described inExample 2. PEG-MA Cationic Monomer Brookfield Mn Wt % Type^(a) Wt %Viscosity^(b) Polymer E 1100 48 METAC 52 NA Polymer F 1100 48 APTMAC 52NA Polymer G 1100 37 METAC 63 240 Polymer H 1100 23 METAC 77 360^(a)METAC: (methacryloyloxy)ethyl trimethylammonium chloride APTMAC:(3-acrylamidopropyl)trimethylammonium chloride ^(b)Brookfield viscositywas measured at 70 wt % solution, 20° C. using spindle 02 on model DV-I+Brookfield viscometer.

Example 3

The effect of the Polymer A made in Example 1 on concrete slump wastested against the separate components as illustrated in Table 3.

The copolymer of the current invention was evaluated by measuring theslump of a concrete sample that was formulated as follows: sand (1368lb/yd³), stone (1800 lb/yd³), cement (658 lb/yd³), water (267 lb/yd³),superplasticizer, sodium montmorillonite (0.2% by weight of sand). Forall concrete mixes, an EO/PO superplasticizer was used at 0.12% active(by weight of cement) while the cationic graft polymer as well as itsstarting monomers was tested at a dose of 20 wt % of sodiummontmorillonite.

The addition time is as following. Sand, 20% water, sodiummontmorillonite and the monomers or polymers are added together andmixed for 4 minutes, then stone was added into this mixture and mixedfor another one minute. After that, into this mixture, cement and 80%water were added and mixed for another 2 minutes. And at last, an EO/POsuperplasticizer was added into the above mixture and the mix wasfinished in 7 minutes.

In Table 3, Polymer A was compared with its monomer components (DADMACand 475-PEG-MA) and a control concrete sample that contained “none” ofthese components. As shown in Table 3, Polymer A of this inventionclearly exhibits clay mitigation effect as it provides a higher slumpthan its monomer components and the control sample.

TABLE 3 Concrete test Additive Slump (in) None 2.50 DADMAC 3.50475-PEG-MA 2.75 Polymer A 5.50

Example 4

Using the procedure in Example 3, Polymer E was evaluated, and the testresults are illustrated in Table 4.

In Table 4, Polymer E was compared with its monomer components (METACand 1100-PEG-MA) and a control concrete sample that contained “none” ofthese components. As shown in Table 4, Polymer E clearly provides ahigher slump than its monomer components and the control sample,confirming its clay mitigating effect.

TABLE 4 Concrete Test Additive Slump (in) None 2.50 METAC 3.001100-PEG-MA 2.75 Polymer E 5.75

Example 5

Using the procedure in Example 3, Polymer F was evaluated. The concretetest result is illustrated in Table 5. In Table 5, Polymer F wascompared with its monomer components (APTAC and 1100-PEG-MA) and acontrol concrete sample that contained “none” of these components. Theresults in Table 5 indicate that Polymer F of this invention clearly hasa clay mitigation effect.

TABLE 5 Concrete Test Additive Slump (in) None 2.50 APTAC 3.251100-PEG-MA 2.75 Polymer F 5.50

Example 6

Using the procedure in Example 3 but different polymer dosage, PolymerB, Polymer G and Polymer H were evaluated. The concrete test results areillustrated in Table 6.

In Table 6, three polymers of this invention were compared with acontrol concrete sample that contained “none” of these polymers. Asshown in Table 6, Polymers B, G and H significantly improved slumpperformances than the control sample. When the dosage of the polymer wasincreased from 15% to 25% to dry clay, the slump performance wasincreased as well.

TABLE 6 Concrete Test Slump (in) at dosage of Additive 0 15 wt % to clay25 wt % to clay None 3.00 — — Polymer B 4.25 6.75 Polymer G 5.25 7.00Polymer H 4.50 6.75

Example 7

The effects of the Polymer C and Polymer D on mortar workability weretested against a control mortar sample that contained “none” of thesepolymers. The mortar test results were illustrated in Table 7.

Mortar was prepared in the traditional manner as follows: sand (1350 g),cement (650 g), sodium montmorillonite (2.7 g), water (250 g), EO/POsuperplasticizer (0.12% active by weight of cement), and polymers ofthis invention were added at 5% and 10% based on the weight of sodiummontmorillonite. Sand was blended with sodium montmorillonite and thenblended with the cationic polymer prior to mixing into a mortar. Theworkability was determined by measuring the slump and flow and wascalculated by the following equation: Workability=slump+(flow 1+flow2)/2−100.

As shown in Table 7, the addition of Polymer C or D clearly improvedmortar workability. Increasing the dosage of the polymer led to highermortar workability.

TABLE 7 Mortar test wt % on sodium Workability montmorillonite (mm) None0 75 Polymer C 5 142 Polymer D 5 187 Polymer C 10 236 Polymer D 10 237

The foregoing examples and embodiments were presented for illustrativepurposes only and not intended to limit the scope of the invention.

It is claimed:
 1. A method for treating clay-bearing aggregates used inconstruction materials, comprising: introducing to clay-bearing sandaggregates, in an amount of 5% to 60% based on dry weight of clay, atleast one copolymer obtained from monomer components (A), (B), andoptionally (C), as follows: (A) in an amount of 0.10-0.95 mole, a firstmonomer selected from quarternized vinylpyridine or other cationicmonomer represented by the following structures

wherein R₁, R₂, and R₃ each independently represent hydrogen, —CH₃, or—COOH; R₄, R₅, R₆, R₇, and R₈ each independently represent a C₁-C₄ alkylgroup; R₉ and R₁₀ each independently represent hydrogen or —CH₃; Z₁represents —O— or —NH—; Y₁ represents —CH₂CH(OH)CH₂— or (CH₂)_(n)wherein “n” represents an integer of 0 to 6; and X represents a halide,pseudohalide, or sulfate; (B) in an amount of 0.05-0.90 mole, a secondmonomer represented by the structural formula

wherein R₁₁, R₁₂, R₁₃, R₁₄, and R₁₅ each independently representhydrogen or C₁ to C₃ alkyl; Z₂ represents —O—, —COO—, —OOC—, —COHN—, or—NHCO—; Y₂ represents —(CH₂)_(n)— wherein “n” represents an integer of 0to 6; and “m” represents an integer of 10 to 200; and (C) in an amountof 0-0.20 mole, a third monomer selected from the group consisting ofacrylate, methacrylate, acrylamide, methacrylamide, alkyl or dialkylacrylamide, and methacrylamide monomers.
 2. The method of claim 1wherein said copolymer has a molecular weight of 1,000-100,000.
 3. Themethod of claim 2, wherein said copolymer has a molecular weight of2,000-60,000.
 4. The method of claim 3, wherein said copolymer has amolecular weight of 5,000-50,000.
 5. The method of claim 1 wherein, insaid second monomer component, “m” represents an integer of 10-100. 6.The method of claim 5 wherein, in said second monomer component, “m”represents an integer of 20-70.
 7. The method of claim 1 wherein themolar ratio (A:B) of said first monomer component (A) to said secondmonomer component (B) is 0.20:0.80 to 0.90:0.10.
 8. The method of claim7 wherein the molar ratio (A:B) of said first monomer component (A) tosaid second monomer component (B) is 0.50:0.50 to 0.85:0.15.
 9. Themethod of claim 1 wherein each of R₇ and R₈ are —CH₃ groups, and each ofR₉ and R₁₀ are hydrogen.
 10. The method of claim 1 wherein Z₁ is oxygenand Y₁ is —CH₂CH₂—.
 11. The method of claim 1 wherein Z₁ is —NH— and Y₁is —CH₂CH₂CH₂—.
 12. The method of claim 1 wherein said copolymer has twoor more monomer components which are represented by one or saidstructures of said first monomer component (A).
 13. The method of claim1 wherein said copolymer has two or more monomer components which arerepresented by said structure of said first monomer component (B). 14.The method of claim 1 wherein said copolymer has a Brookfield viscosityof 20 to 2000 cps at 70 wt % aqueous solution at 20° C.
 15. The methodof claim 14 wherein said copolymer has a Brookfield viscosity of 60 to500 cps at 70 wt % aqueous solution at 20° C.
 16. The method of claim 1wherein the amount of said copolymer introduced to said clay is 10% to40% by weight based on the weight of the clay.
 17. The method of claim16 wherein the amount of said copolymer introduced to said clay is 10%to 30% by weight based on the weight of the clay.
 18. The method ofclaim 1 wherein said copolymer is introduced to said clay separately,followed by addition of a water reducing admixture.
 19. The method ofclaim 1 wherein said copolymer is introduced to said clay together withan EO/PO polycarboxylate superplasticizer.
 20. A composition obtainedfrom the method of claim 1.